A radio frequency transmit coil assembly for magnetic resonance imaging of a subject's ankle

Abstract

The application relates to the technical field of magnetic resonance, in particular to a radio frequency transmitting coil assembly for performing magnetic resonance imaging on an ankle of a subject. The radio frequency transmitting coil assembly comprises: a chamber configured to accommodate the ankle and a rear part of a foot of the subject; a radio frequency transmitting coil arranged around the chamber and configured to transmit a radio frequency signal to the ankle; and an opening part in communication with the chamber and configured to allow a front part of the foot to extend in.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging technology, and more particularly to a radio frequency transmitting coil assembly for performing magnetic resonance imaging on the ankle of a subject. Background Technology

[0002] The radio frequency (RF) transmitting coil assembly mainly consists of a coil and a support for the carrying coil. It is used to transmit radio frequency signals to the target limb of the subject to excite the hydrogen nuclei in the target limb to generate magnetic resonance signals, and based on this, obtain magnetic resonance images of the target limb.

[0003] In ultra-high field magnetic resonance systems such as 7.0T, since there is no universally applicable large-size RF transmitting coil, the RF receiving coil channels used in such systems all need to have transmitting capabilities. The efficiency of the transmitting coil is directly related to SAR safety and power amplifier output power; to achieve higher transmission efficiency, the size of the transmitting coil needs to be as small as possible. For special limb areas such as the ankle, if a corresponding transmitting coil is to be designed, how to reduce the size of the transmitting coil to improve its transmission efficiency is the research topic of this application. Summary of the Invention

[0004] In view of this, this application provides a radio frequency transmitting coil assembly for performing magnetic resonance imaging on the ankle of a subject.

[0005] This application discloses a radio frequency transmitting coil assembly for performing magnetic resonance imaging on the ankle of a subject, comprising:

[0006] A chamber is configured to accommodate the rear portion of the subject's ankle and foot;

[0007] An RF transmitting coil, arranged around the cavity, is used to transmit radio frequency signals to the ankle;

[0008] An opening, communicating with the chamber, is configured to allow the front portion of the foot to extend into it.

[0009] In some possible implementations, the opening communicates with the external environment of the component, and the opening is configured to allow the front portion of the foot to extend into and out.

[0010] In some possible implementations, the RF transmitting coil is formed in a cylindrical shape, with the front half of the foot extending to the outer periphery of the RF transmitting coil.

[0011] In some possible implementations, the RF transmitting coil is a birdcage coil, which includes:

[0012] The first and second end rings are arranged spaced apart along the length of the subject and extend around the chamber.

[0013] Multiple legs are arranged at intervals in the circumferential direction around the chamber and connect the first end ring and the second end ring;

[0014] The opening is located between the first and second adjacent legs among the plurality of legs.

[0015] In some possible implementations, the first leg includes:

[0016] The first segment extends from the first end ring along the length of the body toward the second end ring;

[0017] The second segment is closer to the second end ring in the length direction than the first segment, and farther away from the second leg in the circumferential direction than the first segment;

[0018] The second leg includes:

[0019] The third segment extends from the first end ring along the length of the body toward the second end ring;

[0020] The fourth segment is closer to the second end ring in the length direction than the third segment, and farther away from the first leg in the circumferential direction than the fourth segment;

[0021] The opening is located between the second segment and the fourth segment.

[0022] In some possible implementations, the first segment, the third segment, and all other legs of the birdcage coil, except for the first and second legs, are arranged at equal angles in the circumferential direction;

[0023] When viewed along the length of the body, both the first segment and the third segment fall into the opening.

[0024] The components described in some possible implementations include:

[0025] The lower portion is configured to support the ankle;

[0026] The upper portion is detachably mounted to the upper side of the lower portion and has the opening.

[0027] The chamber is defined by the lower portion and the upper portion, and the RF transmitting coil is mounted on the upper portion and the lower portion;

[0028] After the ankle is supported on the lower portion with the subject's toes pointing upwards, the upper portion is attached to the lower portion from the upper side with the opening aligned with the toes.

[0029] The components described in some possible implementations include:

[0030] A footrest, located within the cavity, is configured to support the ankle by supporting the subject's heel.

[0031] In some possible implementations, the RF transmitting coil includes a plurality of coil units, and a first coil unit of the plurality of coil units is arranged around the opening.

[0032] In some possible implementations, the first coil unit is a toroidal coil unit and includes a first half located at the opening and a second half located away from the opening, wherein the dimension of the first half in the left-right direction of the foot is greater than the dimension of the second half in the left-right direction of the foot.

[0033] The radio frequency transmission coil assembly for magnetic resonance imaging of a subject's ankle provided in the embodiments of this application has an opening for the front part of the subject's foot, such as the toes, to insert or even extend, which can effectively reduce the size of the RF transmission coil, thereby providing higher transmission efficiency and lower SAR security risks. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this application, and are not intended to limit this application.

[0035] Figure 1 This is a schematic diagram of the radio frequency transmitting coil assembly provided in an embodiment of this application in its use state.

[0036] Figure 2 yes Figure 1 A schematic diagram of the RF transmitting coil assembly after the housing on the upper part has been opened.

[0037] Figure 3 yes Figure 2 Top view.

[0038] Figure 4 yes Figure 1 A schematic diagram showing the RF transmitter coil assembly after the upper part has been removed.

[0039] Figure 5 yes Figure 4 A schematic diagram of the structure after the subject's limb has been removed.

[0040] Figure 6 This is a schematic diagram of a birdcage-type RF transmitting coil provided in one embodiment of this application after being unfolded circumferentially, and the location of the opening is shown.

[0041] Figure 7 This is a schematic diagram of a birdcage-type RF transmitting coil provided in another embodiment of this application after being unfolded circumferentially, and it shows the location of the opening.

[0042] Figure 8 This is a schematic diagram of an array coil type RF transmitting coil provided in another embodiment of this application after being unfolded circumferentially, and the location of the opening is shown.

[0043] Figure 9 This is a schematic diagram of an array coil type RF transmitting coil provided in another embodiment of this application after being unfolded circumferentially, and the location of the opening is shown.

[0044] Explanation of reference numerals in the attached figures:

[0045] p1 - ​​foot, p1F - front part, p1B - front part;

[0046] p2 - Ankle;

[0047] p3 - Lower leg;

[0048] DR1 - length direction, DR2 - circumferential direction;

[0049] 100-RF transmitting coil assembly;

[0050] 1U - upper part, 1D - lower part;

[0051] 2-chamber;

[0052] 3-RF transmitting coil;

[0053] 4-Birdcage coil;

[0054] 5-First end ring;

[0055] 6-Second end ring;

[0056] 7-legs;

[0057] 7L - First leg, 7L1 - First segment, 7L2 - Second segment, 7L3 - First connecting segment;

[0058] 7R - Second leg, 7R1 - Third segment, 7R2 - Fourth segment, 7R3 - Second connecting segment;

[0059] 8-Opening;

[0060] 9-Ring coil unit;

[0061] 9A - First coil unit, 9A1 - First half-ring, 9A2 - Second half;

[0062] 10-Footrest. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the described embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It is understood that, without conflict, some technical means of the various embodiments described herein can be substituted for or combined with each other.

[0064] In the description of this application, the terms "first," "second," etc., are used only to distinguish the described objects and have no sequential or technical meaning. Therefore, objects specified with "first," "second," etc., may explicitly or implicitly include one or more of those objects, and, for example, the term "first element" itself does not imply the existence of a "second element," nor does the term "second element" itself imply the existence of a "first element." Furthermore, words such as "a" or "one" do not indicate a quantity limitation, but rather indicate the presence of at least one, while "multiple" indicates not less than two.

[0065] Figures 1 to 5 A radio frequency transmitting coil assembly 100 (hereinafter, sometimes simply referred to as the assembly 100) provided according to an embodiment of this application is shown, which is suitable for magnetic resonance imaging of the ankle p2 of a subject.

[0066] The component 100 includes an upper portion 1U and a lower portion 1D, the upper portion 1U being detachably mounted to the upper side of the lower portion 1D. Each of the upper portion 1U and the lower portion 1D includes a housing made substantially entirely of plastic and omitting markings, and a conductor mounted inside the housing for forming an RF transmitting coil 3, the conductor may include, for example, a strip of copper foil or a wire.

[0067] The upper portion 1U is formed into a generally semi-circular plate shape, with a generally semi-cylindrical first groove that is recessed upwards from the bottom. An opening 8, extending vertically through the upper portion 1U, is formed approximately in the middle of the upper portion 1U. This opening 8 is shown as square in the figure, but is not limited to this; for example, the opening 8 can be formed as circular, elliptical, or other arbitrary shapes. Furthermore, the upper half of the birdcage coil 4, which serves as the RF transmitting coil 3, is installed within the housing of the upper portion 1U.

[0068] The lower portion 1D has a generally semi-cylindrical second groove that is recessed downwards from the top and has a flat bottom surface so that the assembly 100 can be placed stably on a horizontal support surface. In addition, the lower half of the birdcage coil 4 is installed inside the housing of the lower portion 1D.

[0069] When the upper portion 1U and the lower portion 1D are assembled together, the two (more specifically, the first groove and the second groove) together define a generally cylindrical cavity 2, and the upper half of the birdcage coil 4 and the lower half of the birdcage coil 4 are electrically connected to each other based on the assembly of the upper portion 1U and the lower portion 1D, thereby forming a complete birdcage coil 4 arranged around the cavity 2, and the opening 8 communicates with the cavity 2.

[0070] In use, chamber 2 accommodates the entire ankle p2, the posterior portion p1B of foot p1, and the lower portion of lower leg p3 of the subject. Opening 8 allows the posterior portion p1F of foot p1 to extend into it. Birdcage coil 4 transmits radio frequency signals to ankle p2 (and surrounding tissue). This method avoids the need to significantly increase the overall volume of chamber 2 to accommodate the entire foot p1, thus reducing the size of chamber 2 and consequently the distance between RF transmission coil 3 and ankle p2. This improves the transmission efficiency of RF transmission coil 3, reduces SAR safety risks, and yields high-quality magnetic resonance images. Furthermore, it also prevents the component 100 from becoming excessively large.

[0071] It should be understood that the forefoot portion p1F of foot p1 is the part on the toe side, and the posterior portion p1B of foot p1 is the part on the heel side. For example, the forefoot portion p1F of foot p1 may include the toes and the forefoot, and the posterior portion p1B of foot p1 includes the heel and the hindfoot.

[0072] In this embodiment, the opening 8 is in communication with the external environment of the component 100. Based on this, in some application scenarios, the front part p1F of the subject's foot p1 not only extends into the opening 8, but also extends out of the opening 8 into the external environment.

[0073] The birdcage coil 4 is cylindrical and includes a first end ring 5 and a second end ring 6 arranged at intervals along the length direction DR1 of the subject and surrounding the chamber 2, and a plurality of legs 7 arranged at intervals along the circumferential direction DR2 surrounding the chamber 2 and connecting the first end ring 5 and the second end ring 6, wherein the opening 8 is disposed between adjacent first legs 7L and second legs 7R among the plurality of legs 7.

[0074] In some embodiments, the birdcage coil 4 has a total of 16 legs 7. The upper half of the first end ring 5 and the upper half of the second end ring 6 are installed in the housing of the upper part 1U, and each has an electrical connection male on both sides of the slot of the first groove; the lower half of the first end ring 5 and the lower half of the second end ring 6 are installed in the housing of the lower part 1D, and each has an electrical connection female on both sides of the slot of the second groove; 8 of the 16 legs 7 are installed in the housing of the upper part 1U and are connected to the upper half of the first end ring 5 and the upper half of the second end ring 6; the other 8 of the 16 legs 7 are installed in the housing of the lower part 1D and are connected to the lower half of the first end ring 5 and the lower half of the second end ring 6. When the upper part 1U is installed onto the lower part 1D, the aforementioned male electrical connector is inserted into the aforementioned female electrical connector to achieve electrical connection between the upper half ring and the lower half ring, thereby forming a complete first end ring 5 and a second end ring 6, and thus forming a complete birdcage coil 4.

[0075] If the number of legs 7 of the birdcage coil 4 is small, it is not conducive to obtaining high-quality magnetic resonance images. However, if the number of legs 7 of the birdcage coil 4 is increased, the spacing between adjacent legs 7 will be closer, which may make it difficult to leave enough space to arrange the opening 8 with the required size, especially when the birdcage coil 4 is designed to be small in size and close to the ankle p2. However, the inventors have solved this problem by constructing a portion of the first leg 7L and the second leg 7R to be more distant from each other in the circumferential direction DR2 (i.e., the arrangement direction of the legs 7) than the other portions of the first leg 7L and the second leg 7R.

[0076] Specifically, please see Figure 2 and Figure 3 The first leg 7L includes a first segment 7L1, a second segment 7L2, and a first connecting segment 7L3 connecting the first segment 7L1 and the second segment 7L2. The first segment 7L1 extends from the first end ring 5 along the body length direction DR1 toward the second end ring 6. The first connecting segment 7L3 extends from the end of the first segment 7L1 near the second end ring 6, inclined relative to the body length direction DR1 and gradually moving away from the second leg 7R in the circumferential direction DR2, toward the second end ring 6. The second segment 7L2 extends from the end of the first connecting segment 7L3 near the second end ring 6 along the body length direction DR1 toward the second end ring 6. Therefore, in the body length direction DR1, the second segment 7L2 is closer to the second end ring 6 than the first segment 7L1, and in the circumferential direction DR2, the second segment 7L2 is farther away from the second leg 7R than the first segment 7L1.

[0077] Similar to the first leg 7L, the second leg 7R includes a third segment 7R1, a fourth segment 7R2, and a second connecting segment 7R3 connecting the third segment 7R1 and the fourth segment 7R2. The third segment 7R1 extends from the first end ring 5 along the body length direction DR1 toward the second end ring 6. The second connecting segment 7R3 extends from the end of the third segment 7R1 near the second end ring 6, inclined relative to the body length direction DR1 and gradually moving away from the first leg 7L in the circumferential direction DR2, toward the second end ring 6. The fourth segment 7R2 extends from the end of the second connecting segment 7R3 near the second end ring 6 along the body length direction DR1 toward the second end ring 6. Therefore, in the body length direction DR1, the fourth segment 7R2 is closer to the second end ring 6 than the third segment 7R1, and in the circumferential direction DR2, the fourth segment 7R2 is farther away from the first leg 7L than the third segment 7R1. With this design, without increasing the overall distance between the first leg 7L and the second leg 7R, a relatively large gap is formed between the second segment 7L2 of the first leg 7L and the fourth segment 7R2 of the second leg 7R, so that the aforementioned opening 8 can be arranged in this part. The opening 8 is arranged between the second segment 7L2 and the fourth segment 7R2. Therefore, the size of the opening 8 can be designed to be large enough to accommodate various leg sizes, and the uniformity of the radio frequency signal emitted by the RF transmitting coil 3 will not be significantly reduced.

[0078] The front half of the subject's foot extends from between the first leg 7L and the second leg 7R to the outer periphery of the RF transmitting coil 3.

[0079] Furthermore, in this embodiment, the first segment 7L1 of the first leg 7L, the third segment 7R1 of the second leg 7R, and all other legs 7 of the birdcage coil 4, except for the aforementioned first leg 7L and second leg 7R, are arranged at equal angles on the circumferential DR2. This design better suppresses the influence of the biased second segment 7L2 and fourth segment 7R2 on the uniformity of the radio frequency signal emitted by the RF transmitting coil 3.

[0080] In this embodiment, the first segment 7L1, the first connecting segment 7L3, and the second segment 7L2 of the first leg 7L, and the third segment 7R1, the second connecting segment 7R3, and the fourth segment 7R2 of the first leg 7R are all straight-line extension segments. In other embodiments, at least one of the first segment 7L1, the first connecting segment 7L3, and the second segment 7L2 (e.g., the first connecting segment 7L3 and / or the second segment 7L2) is a curved segment extending in an arc shape, and at least one of the third segment 7R1, the second connecting segment 7R3, and the fourth segment 7R2 (e.g., the second connecting segment 7R3 and / or the fourth segment 7R2) is also a curved segment extending in an arc shape.

[0081] Furthermore, when viewed along the length direction DR1, the first segment 7L1 of the first leg 7L and the third segment 7R1 of the second leg 7R both fall into the opening 8.

[0082] The component 100 is designed to include a detachable upper portion 1U and a lower portion 1D, and the opening 8 is located in the upper portion 1U. This design has the advantage that, during use, the subject's ankle p2 can be supported on the lower portion with the toes pointing upwards, and then the upper portion 1U can be installed from above onto the lower portion 1D with the opening 8 aligned with the toes. Therefore, the ankle p2 can be easily placed into the small chamber 2.

[0083] Additionally, the component 100 includes a footrest 10 disposed within the chamber 2, the footrest 10 being configured to support the ankle p2 by supporting the subject's heel. In some embodiments, the footrest 10 also directly supports the subject's lower leg P3.

[0084] In some embodiments, the footrest 10 may be a component attached to the lower portion 1D in the second recess using bolts or other fasteners. In other embodiments, the footrest 10 is integrally formed with the housing of the lower portion 1D, wherein a portion of the inner wall surface of the second recess (which is also the outer surface of the housing of the lower portion 1D) protrudes upward to define the footrest 10 for direct support of the heel.

[0085] In addition, such as Figure 4 and Figure 5 As shown, the footrest 10 also has a vertical support portion for supporting the subject's foot p1 from the foot side.

[0086] exist Figures 1 to 5 In one embodiment, the second segment 7L2 is located midway along the first leg 7L, and the fourth segment 7R2 is located midway along the second leg 7R. However... Figure 6 The other embodiment shown is different, in Figure 6 In the middle, the second segment 7L2 is located at the end side of the first leg 7L, and it is directly connected to the second end ring 6, and the fourth segment 7R2 is located at the end side of the second leg 7R, and it is directly connected to the second end ring 6.

[0087] In yet another embodiment, such as Figure 7 As shown, the first leg 7L and the second leg 7R are both straight structures extending along the body length direction DR1. That is, compared with the other legs 7 of the birdcage coil 4, the configuration of the first leg 7L and the second leg 7R has not been modified.

[0088] exist Figures 1 to 7 In the various embodiments shown, the RF transmitting coil 3 is a birdcage coil 4. However... Figure 8 and Figure 9 The two embodiments shown are different, in Figure 8 and Figure 9In this configuration, the RF transmitting coil 3 is an array coil composed of multiple ring coil units 9, which are arranged around the cavity 2 in such a way that any two adjacent ring coil units 9 partially overlap each other. Furthermore, one of the ring coil units 9, namely the first coil unit 9A, is arranged around the opening 8.

[0089] exist Figure 8 In one embodiment, multiple ring coil units 9 are formed to have the same shape and size. However... Figure 9 This is different in the embodiments, in Figure 9 In order to obtain a larger size of the opening 8, the first coil unit 9A is designed as follows: the first coil unit 9A has a first half located at the opening 8 and a second half 9A2 away from the opening 8, wherein the dimension of the first half in the left-right direction along foot p1 is greater than the dimension of the second half 9A2 in the left-right direction along foot p1.

Claims

1. A radio frequency transmit coil assembly for magnetic resonance imaging of an ankle of a subject, the radio frequency transmit coil assembly comprising: include: A chamber is configured to accommodate the rear portion of the subject's ankle and foot; An RF transmitting coil, arranged around the cavity, is used to transmit radio frequency signals to the ankle; An opening, communicating with the chamber, is configured to allow the front portion of the foot to extend into it.

2. The assembly of claim 1, wherein, The opening communicates with the external environment of the component and is configured to allow the front portion of the foot to extend into and out.

3. The assembly of claim 1, wherein, The RF transmitting coil is formed into a cylindrical shape, and the front half of the foot extends to the outer periphery of the RF transmitting coil.

4. The component according to claim 3, characterized in that, The RF transmitting coil is a birdcage coil, and the birdcage coil includes: The first and second end rings are arranged spaced apart along the length of the subject and extend around the chamber. Multiple legs are arranged at intervals in the circumferential direction around the chamber and connect the first end ring and the second end ring; The opening is located between the first and second adjacent legs among the plurality of legs.

5. The component according to claim 4, characterized in that, The first leg includes: The first segment extends from the first end ring along the length of the body toward the second end ring; The second segment is closer to the second end ring in the length direction than the first segment, and farther away from the second leg in the circumferential direction than the first segment; The second leg includes: The third segment extends from the first end ring along the length of the body toward the second end ring; The fourth segment is closer to the second end ring in the length direction than the third segment, and farther away from the first leg in the circumferential direction than the fourth segment; The opening is located between the second segment and the fourth segment.

6. The assembly of claim 5, wherein, The first segment, the third segment, and all other legs of the birdcage coil, except for the first and second legs, are arranged at equal angles in the circumferential direction; When viewed along the length of the body, both the first segment and the third segment fall into the opening.

7. The assembly of claim 1, wherein, The components include: The lower portion is configured to support the ankle; The upper portion is detachably mounted to the upper side of the lower portion and has the opening. The chamber is defined by the lower portion and the upper portion, and the RF transmitting coil is mounted on the upper portion and the lower portion; After the ankle is supported on the lower portion with the subject's toes pointing upwards, the upper portion is attached to the lower portion from the upper side with the opening aligned with the toes.

8. The assembly of claim 1, wherein, The components include: A footrest, located within the cavity, is configured to support the ankle by supporting the subject's heel.

9. The component according to claim 1, characterized in that, The RF transmitting coil includes multiple coil units, and a first coil unit of the multiple coil units is arranged around the opening.

10. The assembly of claim 9, wherein, The first coil unit is a ring coil unit and includes a first half located at the opening and a second half away from the opening, wherein the dimension of the first half in the left-right direction of the foot is greater than the dimension of the second half in the left-right direction of the foot.

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